Microsoft Security Bulletin MS11-035 - Critical

Vulnerability in WINS Could Allow Remote Code Execution (2524426)

Published: May 10, 2011

Version: 1.0

General Information

Executive Summary

This security update resolves a privately reported vulnerability in the Windows Internet Name Service (WINS). The vulnerability could allow remote code execution if a user received a specially crafted WINS replication packet on an affected system running the WINS service. By default, WINS is not installed on any affected operating system. Only customers who manually installed this component are affected by this issue.

This security update is rated Critical for servers running supported editions of Windows Server 2003, Windows Server 2008 (except Itanium), and Windows Server 2008 R2 (except Itanium), on which WINS is installed. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by correcting a logic error that occurs when buffers are passed as parameters. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection for the specific vulnerability entry under the next section, Vulnerability Information.

Recommendation. The majority of customers have automatic updating enabled and will not need to take any action because this security update will be downloaded and installed automatically. Customers who have not enabled automatic updating need to check for updates and install this update manually. For information about specific configuration options in automatic updating, see Microsoft Knowledge Base Article 294871.

For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service.

See also the section, Detection and Deployment Tools and Guidance, later in this bulletin.

Known Issues.Microsoft Knowledge Base Article 2524426 documents the currently known issues that customers may experience when installing this security update. The article also documents recommended solutions for these issues.

Affected and Non-Affected Software

The following software have been tested to determine which versions or editions are affected. Other versions or editions are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, visit Microsoft Support Lifecycle.

*Server Core installation affected. This update applies, with the same severity rating, to supported editions of Windows Server 2008 or Windows Server 2008 R2 as indicated, whether or not installed using the Server Core installation option. For more information on this installation option, see the TechNet articles, Managing a Server Core Installation and Servicing a Server Core Installation. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008 and Windows Server 2008 R2; see Compare Server Core Installation Options.

I am running one of the operating systems that are listed in the Affected Software table. Why am I not being offered the update?The update can only be installed if WINS is installed on the operating systems listed in the Affected Software table. By default, WINS is not installed on these operating systems, so the update will not be offered unless WINS has been installed.

Where are the file information details?Refer to the reference tables in the Security Update Deployment section for the location of the file information details.

I am using an older release of the software discussed in this security bulletin. What should I do?The affected software listed in this bulletin have been tested to determine which releases are affected. Other releases are past their support life cycle. For more information about the product lifecycle, visit the Microsoft Support Lifecycle Web site.

It should be a priority for customers who have older releases of the software to migrate to supported releases to prevent potential exposure to vulnerabilities. To determine the support lifecycle for your software release, see Select a Product for Lifecycle Information. For more information about service packs for these software releases, see Lifecycle Supported Service Packs.

Customers who require custom support for older software must contact their Microsoft account team representative, their Technical Account Manager, or the appropriate Microsoft partner representative for custom support options. Customers without an Alliance, Premier, or Authorized Contract can contact their local Microsoft sales office. For contact information, visit the Microsoft Worldwide Information Web site, select the country in the Contact Information list, and then click Go to see a list of telephone numbers. When you call, ask to speak with the local Premier Support sales manager. For more information, see the Microsoft Support Lifecycle Policy FAQ.

Vulnerability Information

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the May bulletin summary. For more information, see Microsoft Exploitability Index.

*Server Core installation affected. This update applies, with the same severity rating, to supported editions of Windows Server 2008 or Windows Server 2008 R2 as indicated, whether or not installed using the Server Core installation option. For more information on this installation option, see the TechNet articles, Managing a Server Core Installation and Servicing a Server Core Installation. Note that the Server Core installation option does not apply to certain editions of Windows Server 2008 and Windows Server 2008 R2; see Compare Server Core Installation Options.

A remote code execution vulnerability exists in the Windows Internet Name Service (WINS) due to insufficient validations for the data structures within specially crafted WINS network packets sent to the WINS service.

To view this vulnerability as a standard entry in the Common Vulnerabilities and Exposures list, see CVE-2011-1248.

Mitigation refers to a setting, common configuration, or general best-practice, existing in a default state, that could reduce the severity of exploitation of a vulnerability. The following mitigating factors may be helpful in your situation:

By default, WINS is not installed on any affected operating system. Only customers who manually install this component are affected by this issue.

Workaround refers to a setting or configuration change that does not correct the underlying vulnerability but would help block known attack vectors before you apply the update. Microsoft has tested the following workarounds and states in the discussion whether a workaround reduces functionality:

Block TCP port 42 and UDP port 42 at your firewall.

These ports are used to initiate a connection with the affected component. Blocking them at the enterprise firewall, both inbound and outbound, will help protect systems that are behind that firewall from attempts to exploit this vulnerability. We recommend that you block all unsolicited inbound communication from the Internet to help prevent attacks that may use other ports. For more information about ports, see TechNet article, TCP and UDP Port Assignments. For more information about the Windows Firewall, see TechNet article, How to Configure Windows Firewall on a Single Computer.

FAQ for WINS Service Failed Response Vulnerability - CVE-2011-1248

What is the scope of the vulnerability?This is a remote code execution vulnerability. An attacker who successfully exploited this vulnerability could run arbitrary code with elevated privileges on vulnerable systems. An attacker could then install programs or view, change, or delete data; or create new accounts with full user rights.

What causes the vulnerability?Due to a logic error when WINS handles a socket send exception, certain user-supplied values remain within a stack frame and are reused in another context. A remote attacker who successfully exploited this vulnerability could corrupt memory in a way that could lead to remote code execution. An attacker could then take control of the system under the System context for Windows Server 2003 or the Local Service context for Windows Server 2008 and Windows Server 2008 R2.

What is WINS?The Windows Internet Name Service (WINS) was designed specifically to support NetBIOS over TCP/IP (NetBT). WINS is required for any environment in which users access resources that have NetBIOS names. If you do not use WINS in such a network, you cannot connect to a remote network resource by using its NetBIOS name unless you use LMHOSTS files, and you might be unable to establish file and print sharing connections. For more information, see the TechNet article, What Is WINS?

What might an attacker use the vulnerability to do?An attacker who successfully exploited this vulnerability could run arbitrary code. An attacker could then install programs; view, change, or delete data; or create new accounts with the permissions of the WINS service.

How could an attacker exploit the vulnerability?An attacker could exploit this vulnerability by creating specially crafted packets and sending the packets to an affected WINS system.

What systems are primarily at risk from the vulnerability?WINS servers running on Windows Server 2003, Windows Server 2008, or Windows Server 2008 R2 are primarily at risk from the vulnerability.

What does the update do?The update corrects the logic error of violating the contract between functions while passing buffers as parameters.

When this security bulletin was issued, had this vulnerability been publicly disclosed?No. Microsoft received information about this vulnerability through coordinated vulnerability disclosure.

When this security bulletin was issued, had Microsoft received any reports that this vulnerability was being exploited?No. Microsoft had not received any information to indicate that this vulnerability had been publicly used to attack customers when this security bulletin was originally issued.

Finally, security updates can be downloaded from the Microsoft Update Catalog. The Microsoft Update Catalog provides a searchable catalog of content made available through Windows Update and Microsoft Update, including security updates, drivers and service packs. By searching using the security bulletin number (such as, "MS07-036"), you can add all of the applicable updates to your basket (including different languages for an update), and download to the folder of your choosing. For more information about the Microsoft Update Catalog, see the Microsoft Update Catalog FAQ.

Detection and Deployment Guidance

Microsoft provides detection and deployment guidance for security updates. This guidance contains recommendations and information that can help IT professionals understand how to use various tools for detection and deployment of security updates. For more information, see Microsoft Knowledge Base Article 961747.

Microsoft Baseline Security Analyzer

Microsoft Baseline Security Analyzer (MBSA) allows administrators to scan local and remote systems for missing security updates as well as common security misconfigurations. For more information about MBSA, visit Microsoft Baseline Security Analyzer.

The following table provides the MBSA detection summary for this security update.

Note Microsoft discontinued support for SMS 2.0 on April 12, 2011. For SMS 2003, Microsoft also discontinued support for the Security Update Inventory Tool (SUIT) on April 12, 2011. Customers are encouraged to upgrade to System Center Configuration Manager 2007. For customers remaining on SMS 2003 Service Pack 3, the Inventory Tool for Microsoft Updates (ITMU) is also an option.

Updates often write to the same files and registry settings required for your applications to run. This can trigger incompatibilities and increase the time it takes to deploy security updates. You can streamline testing and validating Windows updates against installed applications with the Update Compatibility Evaluator components included with Application Compatibility Toolkit.

The Application Compatibility Toolkit (ACT) contains the necessary tools and documentation to evaluate and mitigate application compatibility issues before deploying Microsoft Windows Vista, a Windows Update, a Microsoft Security Update, or a new version of Windows Internet Explorer in your environment.

Deployment Information

When you install this security update, the installer checks whether one or more of the files that are being updated on your system have previously been updated by a Microsoft hotfix.

If you have previously installed a hotfix to update one of these files, the installer copies the RTMQFE, SP1QFE, or SP2QFE files to your system. Otherwise, the installer copies the RTMGDR, SP1GDR, or SP2GDR files to your system. Security updates may not contain all variations of these files. For more information about this behavior, see Microsoft Knowledge Base Article 824994.

Unattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of Setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.

/quiet

Quiet mode. This is the same as unattended mode, but no status or error messages are displayed.

Restart Options

/norestart

Does not restart when installation has completed.

/forcerestart

Restarts the computer after installation and force other applications to close at shutdown without saving open files first.

/warnrestart[:x]

Presents a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.

/promptrestart

Displays a dialog box prompting the local user to allow a restart.

Special Options

/overwriteoem

Overwrites OEM files without prompting.

/nobackup

Does not back up files needed for uninstall.

/forceappsclose

Forces other programs to close when the computer shuts down.

/log:path

Allows the redirection of installation log files.

/integrate:path

Integrates the update into the Windows source files. These files are located at the path that is specified in the switch.

/extract[:path]

Extracts files without starting the Setup program.

/ER

Enables extended error reporting.

/verbose

Enables verbose logging. During installation, creates %Windir%\CabBuild.log. This log details the files that are copied. Using this switch may cause the installation to proceed more slowly.

Note You can combine these switches into one command. For backward compatibility, the security update also supports many of the setup switches that the earlier version of the Setup program uses. For more information about the supported installation switches, see Microsoft Knowledge Base Article 262841.

Removing the Update

This security update supports the following setup switches.

Supported Spuninst.exe Switches

Switch

Description

/help

Displays the command-line options.

Setup Modes

/passive

Unattended Setup mode. No user interaction is required, but installation status is displayed. If a restart is required at the end of Setup, a dialog box will be presented to the user with a timer warning that the computer will restart in 30 seconds.

/quiet

Quiet mode. This is the same as unattended mode, but no status or error messages are displayed.

Restart Options

/norestart

Does not restart when installation has completed.

/forcerestart

Restarts the computer after installation and force other applications to close at shutdown without saving open files first.

/warnrestart[:x]

Presents a dialog box with a timer warning the user that the computer will restart in x seconds. (The default setting is 30 seconds.) Intended for use with the /quiet switch or the /passive switch.

/promptrestart

Displays a dialog box prompting the local user to allow a restart.

Special Options

/forceappsclose

Forces other programs to close when the computer shuts down.

/log:path

Allows the redirection of installation log files.

Verifying that the Update Has Been Applied

Microsoft Baseline Security Analyzer

To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

File Version Verification

Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

Click Start, and then click Search.

In the Search Results pane, click All files and folders under Search Companion.

In the All or part of the file name box, type a file name from the appropriate file information table, and then click Search.

In the list of files, right-click a file name from the appropriate file information table, and then click Properties.

Note Depending on the edition of the operating system, or the programs that are installed on your system, some of the files that are listed in the file information table may not be installed.

On the Version tab, determine the version of the file that is installed on your system by comparing it to the version that is documented in the appropriate file information table.

Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

Registry Key Verification

You may also be able to verify the files that this security update has installed by reviewing the registry keys listed in the Reference Table in this section.

These registry keys may not contain a complete list of installed files. Also, these registry keys may not be created correctly when an administrator or an OEM integrates or slipstreams this security update into the Windows installation source files.

Windows Server 2008 (all editions)

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Inclusion in Future Service Packs

The update for this issue will be included in a future service pack or update rollup

Deployment

Installing without user intervention

For all supported 32-bit editions of Windows Server 2008:Windows6.0-KB2524426-x86.msu /quiet

For all supported x64-based editions of Windows Server 2008:Windows6.0-KB2524426-x64.msu /quiet

This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

HotPatching

Not applicable.

Removal Information

WUSA.exe does not support uninstall of updates. To uninstall an update installed by WUSA, click Control Panel, and then click Security. Under Windows Update, click View installed updates and select from the list of updates.

To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

File Version Verification

Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

Click Start and then enter an update file name in the Start Search box.

When the file appears under Programs, right-click the file name and click Properties.

On the General tab, compare the file size with the file information tables provided in the bulletin KB article.

Note Depending on the edition of the operating system, or the programs that are installed on your system, some of the files that are listed in the file information table may not be installed.

You can also click the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.

Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

Finally, you can also click the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Windows Server 2008 R2 (all editions)

Reference Table

The following table contains the security update information for this software. You can find additional information in the subsection, Deployment Information, in this section.

Inclusion in Future Service Packs

The update for this issue will be included in a future service pack or update rollup

This update does not require a restart. The installer stops the required services, applies the update, and then restarts the services. However, if the required services cannot be stopped for any reason, or if required files are being used, this update will require a restart. If this behavior occurs, a message appears that advises you to restart.

HotPatching

Not applicable.

Removal Information

To uninstall an update installed by WUSA, use the /Uninstall setup switch or click Control Panel, click System and Security, and then under Windows Update, click View installed updates and select from the list of updates.

To verify that a security update has been applied to an affected system, you may be able to use the Microsoft Baseline Security Analyzer (MBSA) tool. See the section, Detection and Deployment Tools and Guidance, earlier in this bulletin for more information.

File Version Verification

Because there are several editions of Microsoft Windows, the following steps may be different on your system. If they are, see your product documentation to complete these steps.

Click Start and then enter an update file name in the Start Search box.

When the file appears under Programs, right-click the file name and click Properties.

On the General tab, compare the file size with the file information tables provided in the bulletin KB article.

Note Depending on the edition of the operating system, or the programs that are installed on your system, some of the files that are listed in the file information table may not be installed.

You can also click the Details tab and compare information, such as file version and date modified, with the file information tables provided in the bulletin KB article.

Note Attributes other than the file version may change during installation. Comparing other file attributes to the information in the file information table is not a supported method of verifying that the update has been applied. Also, in certain cases, files may be renamed during installation. If the file or version information is not present, use one of the other available methods to verify update installation.

Finally, you can also click the Previous Versions tab and compare file information for the previous version of the file with the file information for the new, or updated, version of the file.

Other Information

Acknowledgments

Microsoft thanks the following for working with us to help protect customers:

Microsoft Active Protections Program (MAPP)

To improve security protections for customers, Microsoft provides vulnerability information to major security software providers in advance of each monthly security update release. Security software providers can then use this vulnerability information to provide updated protections to customers via their security software or devices, such as antivirus, network-based intrusion detection systems, or host-based intrusion prevention systems. To determine whether active protections are available from security software providers, please visit the active protections Web sites provided by program partners, listed in Microsoft Active Protections Program (MAPP) Partners.

Support

Customers in the U.S. and Canada can receive technical support from Security Support or 1-866-PCSAFETY. There is no charge for support calls that are associated with security updates. For more information about available support options, see Microsoft Help and Support.

International customers can receive support from their local Microsoft subsidiaries. There is no charge for support that is associated with security updates. For more information about how to contact Microsoft for support issues, visit the International Support Web site.

Disclaimer

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.